llvm/test/Analysis/ScalarEvolution/scev-expander-reuse-unroll.ll
Wei Mi 8ce317bf15 [UNROLL] Postpone ScalarEvolution::forgetLoop after TripCountSC is expanded
when unroll runtime iteration loop.

In llvm::UnrollRuntimeLoopRemainder, if the loop to be unrolled is the inner
loop inside a loop nest, the scalar evolution needs to be dropped for its
parent loop which is done by ScalarEvolution::forgetLoop. However, we can
postpone forgetLoop to the end of UnrollRuntimeLoopRemainder so TripCountSC
expansion can still reuse existing value.

Differential Revision: https://reviews.llvm.org/D23572


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279748 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-25 16:17:18 +00:00

36 lines
1.2 KiB
LLVM

; RUN: opt < %s -loop-unroll -unroll-runtime -unroll-count=2 -verify-scev-maps -S | FileCheck %s
; Check SCEV expansion uses existing value when unrolling an inner loop with runtime trip count in a loop nest.
; CHECK-LABEL: @foo(
; CHECK: select
; CHECK-NOT: select
; CHECK: ret
define void @foo(i32 %xfL, i32 %scaleL) local_unnamed_addr {
entry:
br label %for.body
for.body: ; preds = %for.body5, %for.body, %entry
%xfL.addr.033 = phi i32 [ %xfL, %entry ], [ %add, %for.body5 ]
%add = add nsw i32 %xfL.addr.033, %scaleL
%shr = ashr i32 %add, 16
%cmp.i = icmp slt i32 0, %shr
%.sroa.speculated = select i1 %cmp.i, i32 0, i32 %shr
%cmp425 = icmp slt i32 0, %.sroa.speculated
br i1 %cmp425, label %for.body5.preheader, label %for.end
for.body5.preheader: ; preds = %for.body
%tmp0 = sext i32 %.sroa.speculated to i64
br label %for.body5
for.body5: ; preds = %for.body5, %for.body5.preheader
%indvars.iv = phi i64 [ 0, %for.body5.preheader ], [ %indvars.iv.next, %for.body5 ]
%indvars.iv.next = add nsw i64 %indvars.iv, 1
%cmp4 = icmp slt i64 %indvars.iv.next, %tmp0
br i1 %cmp4, label %for.body5, label %for.body
for.end:
ret void
}